Thank you for all the suggestions..
The breaking down into smaller tasks and then doing it technique would be very helpful. But, all I have to do is, study (and excercise).
I have 18 subjects that I should know inside out by now, and I don't. The problem is, I don't know how to start. And even if I do start from a random subject, I give up when its tough. It just stops making sense to me. I try to understand it online on youtube etc and end up playing a game or watching a totally unrelated video.
I'm not dumb. I'm pretty smart according to most people. But my grades don't reflect that. I have no idea how I've breezed through until now.
I'll start excercising, though sleep cycle regulation will take some time, so will my next to nothing appetite. I hope I don't give up.

I'm already on another antidepressant. Yes, I have a sedentary lifestyle. At least for the last 3 months. I've tried listing the tasks. But I never do anything past the first 2 or 3.
I will try exercising for sure.